Will Saletan writes about politics, science, technology, and other stuff for Slate. He’s the author of Bearing Right.

The back-and-forth hasn't changed either man's mind. But it has clarified one idea around which the United States could build a fair, sensible, and more assertive position on the Palestinian question: Support Israel on the security issues, not on its moral claims to West Bank land.

In his speech to Congress, Netanyahu made a strong case for security conditions:

In recent years, Israel withdrew from South Lebanon and Gaza. We thought we'd get peace. … Instead, we got 12,000 rockets fired from those areas on our cities, on our children, by Hezbollah and Hamas. The U.N. peacekeepers in Lebanon failed to prevent the smuggling of this weaponry. The European observers in Gaza evaporated overnight. So if Israel simply walked out of the territories, the flow of weapons into a future Palestinian state would be unchecked. Missiles fired from it could reach virtually every home in Israel in less than a minute. … Solid security arrangements on the ground are necessary not only to protect the peace. They are necessary to protect Israel in case the peace unravels.

On this basis, Netanyahu rejected a return to Israel's 1967 borders. He called them "indefensible," noting that they would leave the country only nine miles wide at its narrowest point. He also insisted that a Palestinian state must be "fully demilitarized" and that Israel must "maintain a long-term military presence along the Jordan River."

But Netanyahu also blended these security demands with social, moral, and religious claims. In his initial rebuttal, he challenged Obama to affirm that Israel would not have "to withdraw to the 1967 lines which are both indefensible and which would leave major Israeli population centers in Judea and Samaria beyond those lines." In his address to Congress, the prime minister noted that "the vast majority of the 650,000 Israelis who live beyond the 1967 lines reside in neighborhoods and suburbs of Jerusalem and Greater Tel Aviv." He declared that "under any realistic peace agreement, these areas, as well as other places of critical strategic and national importance, will be incorporated into the final borders of Israel."

"Strategic and national importance" is the giveaway phrase. It shows how Netanyahu smuggles moral claims into his security arguments. The security arguments are well-founded in Israel's geographic vulnerability and in a history of Palestinian and Arab violence against the Jewish state, including three wars that threatened to annihilate it. But items of "national importance," such as protruding West Bank settlements, have no such justification. If you move people into disputed territory and then claim that territory as an "Israeli population center," good luck selling that argument. The U.S. won't stand behind you.

"In Judea and Samaria, the Jewish people are not foreign occupiers," Netanyahu reminded Congress. "This is the land of our forefathers." But that's also true of the Palestinians. The historical record makes a strong case that Israel, compared to its neighbors, has earned greater respect for its security fears and commitments. The historical record makes no such case for unilateral religious or nationality-based claims to the West Bank.

Obama has promised to meet Israel's security needs. In his address to AIPAC, he pledged to block Iran's nuclear program, stand up to Hezbollah, and supply technologies that "maintain Israel's qualitative military edge." Speaking at the White House alongside Netanyahu, the president affirmed that "Israel's security will remain paramount in U.S. evaluations of any prospective peace deal." At the State Department, Obama added:

Israel must be able to defend itself, by itself, against any threat. Provisions must also be robust enough to prevent a resurgence of terrorism, to stop the infiltration of weapons, and to provide effective border security. The full and phased withdrawal of Israeli military forces should be coordinated with the assumption of Palestinian security responsibility in a sovereign, non-militarized state. And the duration of this transition period must be agreed, and the effectiveness of security arrangements must be demonstrated.

Obama has also vigorously defended Israel's legitimacy as a Jewish state. But he hasn't supported Israel's social or moral claims to territory beyond the 1967 borders. At the State Department, he specifically chided Israel for continuing its "settlement activity."

Critics, following Netanyahu's lead, have accused Obama of endangering Israel by dictating a return to the 1967 borders. But that critique—which overlooks Obama's caveat that the borders would be revised through "mutually agreed swaps" of land—buys into Netanyahu's conflation of Israeli concerns. The dispute between Obama and Netanyahu isn't about returning to indefensible borders. It's about whether defensibility, rather than "population centers," "national importance," and "the 4,000-year-old bond between the Jewish people and the Jewish land," will be the basis for redrawing those borders.

Obama could make this difference explicit. He could declare that while Israel's security will be "paramount in U.S. evaluations of any prospective peace deal," as he pledged on May 20, its social or moral claims to post-1967 territory won't be. Obama already accepts that his security pledge requires a "nonmilitarized" Palestinian state, consistent with Netanyahu's demands. Netanyahu could also argue that it requires an Israeli military presence along the Jordan River for many years before a "full" withdrawal of Israeli forces.

But the security principle wouldn't support Israeli territorial claims to settlements on social or religious grounds. Coupled with the 1967 borders as a starting point, it might force Israel to trade many of these settlements for land of greater strategic importance. And with equal coldness, it would forsake Palestinians' claims of a right to return to their grandparents' long-abandoned property inside the 1967 borders. Security, yes. Historical claims, no.

It would also forsake either side's exclusive claim to Jerusalem. Netanyahu, in his remarks to Congress, insisted that "Jerusalem must never again be divided" because "only a democratic Israel has protected freedom of worship for all faiths in the city." Sorry, but that's not a security argument.

A well-designed security pact might even bypass the Hamas problem. Netanyahu refuses to negotiate with a Palestinian Authority that includes Hamas, since Hamas is sworn to Israel's destruction. The P.A. says Hamas will fall in line if a peace deal is reached. But if a deal can be worked out with security provisions that enable Israel to maintain a military presence and thwart weapons smuggling, isn't that better protection than a few magic—and insincere—words from Hamas?

If Netanyahu doesn't like this security-oriented U.S. policy, he's free to reject or ignore it. We can't make him cut a deal on our terms. But that doesn't mean we have to shut up about our differences. I'm a Jew and a hawk. I've been to Israel on an AIPAC trip. I've seen border posts, met West Bank settlers, and talked with people who lived under bombardment from Gaza. It's a great country. I'd give my life to save it. But I wouldn't give a lot of other people's lives—and leave the embers of Palestinian occupation glowing in the wind of the Arab uprisings—to sustain the fantasy of an Israel bigger than it needs to be.